Globally strong geomagnetic field intensity circa 3000 years ago

Abstract

High-fidelity geomagnetic field intensity determination was carried out using 191 baked fragments collected from 20 kilns or hearths with ages ranging between similar to 1200 BC and similar to AD 1725 in South Korea. Geomagnetic field intensity variation displayed three narrow minima at similar to 800-700 BC, similar to AD 700, and similar to AD 1600 and two maxima at similar to 1200-1100 BC and similar to AD 1000-1100. In most time intervals, virtual axial dipole moment (VADM) variation is confined within 20% of the present VADM. However, geomagnetic field intensity circa 3000 yr ago is nearly 40% larger than the present value. Such high VADMs circa 3000 yr ago are in phase with those in other longitudinal bands in northern hemisphere centered at 5E (France), 30E (the Middle East) and 200E (Hawaii). Although strong geomagnetic field intensity circa 3000 yr ago is globally synchronous, the highest VADM occurs at slightly different time intervals in different locations. Hence it is possible that the globally strong geomagnetic field intensity circa 3000 yr ago reflects the migration of persistent hemispheric flux in northern hemisphere or an episode of geomagnetic field hemispheric asymmetry. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.